Solid electrolyte precursor solution, solid electrolyte, and battery

Abstract

The present application discloses a solid electrolyte precursor solution, a solid electrolyte, and a battery. The solid electrolyte precursor solution comprises a lithium salt solution, pentaerythritol glycidyl ether, and lithium difluoro(oxalato)borate, wherein the lithium salt solution comprises a lithium salt and a solvent. The solid electrolyte prepared from the solid electrolyte precursor solution of the present application has high ionic conductivity.

Description

Solid electrolyte precursor solution, solid electrolyte and battery

[0001] This application claims priority to Chinese Patent Application No. 202411587242.5, filed on November 8, 2024, entitled "Solid Electrolyte Precursor Solution, Solid Electrolyte and Battery and Preparation Method Thereof", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery technology, and more particularly to a solid electrolyte precursor solution, a solid electrolyte, and a battery. Background Technology

[0003] In recent years, safety issues caused by electrolyte leakage have occurred frequently, making the research on solid-state electrolytes imperative. However, the development of solid-state electrolytes is currently hampered by problems such as low ionic conductivity and the difficulty in solving solid-solid interface issues (the interface formed between solid phases, i.e., the interface between the solid electrolyte and the electrode, and the interface between the solid electrolyte and the membrane). Quasi-solid-state electrolytes have become an essential path for liquid electrolytes to evolve into solid-state electrolytes. Among these technologies, in-situ solidification technology has attracted widespread research attention due to its simple process and ease of industrialization.

[0004] However, existing in-situ solid electrolyte precursor solutions require the addition of large amounts of monomers, initiators, and crosslinking agents to polymerize, resulting in low ionic conductivity of the prepared solid electrolytes. Technical solutions

[0005] In view of this, this application provides a solid electrolyte precursor solution, a solid electrolyte, and a battery, aiming to improve the problem of low ionic conductivity of solid electrolytes prepared from existing solid electrolyte precursor solutions.

[0006] The embodiments of this application are implemented as follows: a solid electrolyte precursor solution includes a lithium salt solution, pentaerythritol glycidyl ether, and lithium difluorooxalate borate, wherein the lithium salt solution includes a lithium salt and a solvent.

[0007] Optionally, in some embodiments, the mass ratio of the lithium salt to the solvent is (0.08 to 0.25):1.

[0008] Optionally, in some embodiments, the mass of the lithium difluorooxalate borate is 0.1% to 1% of the mass of the lithium salt solution.

[0009] Optionally, in some embodiments, the mass of the pentaerythritol glycidyl ether is 1.5 to 8% of the mass of the lithium salt solution.

[0010] Optionally, in some embodiments, the lithium salt includes one or more of LiPF6, LiBF4, LiCl, LiAlCl4, LiSbF6, LiSCN, LiCl, LiCF3SO3, LiCF3CO2, LiN(CF3SO2)2, LiAsF6, LiBC4O8, and LiN(FSO2)2.

[0011] Optionally, in some embodiments, the solvent includes one or more of ether solvents, ester solvents, sulfone solvents, and ionic liquid solvents.

[0012] Optionally, in some embodiments, the ether solvent includes one or more of dimethyl ether, ethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, ethylene glycol dibutyl ether, 2,2,2-trifluoroethyl ether, ethylene glycol bis(propionitrile) ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, and triethylene glycol dimethyl ether.

[0013] Optionally, in some embodiments, the ester solvent includes one or more of ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, propylene carbonate, fluoroethylene carbonate, methyl trifluoroethyl carbonate, difluoroethylene carbonate, tris(2,2,2-trifluoroethyl) phosphate, bis(2,2,2-trifluoroethyl) carbonate, and ethyl trifluoroacetate.

[0014] Optionally, in some embodiments, the sulfone solvent includes one or more of sulfolane and dimethyl sulfoxide.

[0015] Optionally, in some embodiments, the ionic liquid solvent includes one or more of 1-methyl-1-propylpyrrolidine bis(fluorosulfonyl)imide, 1-methyl-1-propylpyrrolidine bis(trifluoromethanesulfonyl)imide, N-propyl-N-methylpyrrolidine hexafluorophosphate, N-butyl-N-methylpyrrolidine hexafluorophosphate, and N-ethyl-N-methylpyrrolidine bis(fluorosulfonyl)imide.

[0016] Accordingly, this application also provides a solid electrolyte, wherein the solid electrolyte is obtained by solidifying a solid electrolyte precursor solution, the solid electrolyte precursor solution comprising a lithium salt solution, pentaerythritol glycidyl ether and lithium difluorooxalate borate, wherein the lithium salt solution comprises a lithium salt and a solvent.

[0017] Optionally, in some embodiments, the mass ratio of the lithium salt to the solvent is (0.08 to 0.25):1.

[0018] Optionally, in some embodiments, the mass of the lithium difluorooxalate borate is 0.1% to 1% of the mass of the lithium salt solution.

[0019] Optionally, in some embodiments, the mass of the pentaerythritol glycidyl ether is 1.5 to 8% of the mass of the lithium salt solution.

[0020] Optionally, in some embodiments, the lithium salt includes one or more of LiPF6, LiBF4, LiCl, LiAlCl4, LiSbF6, LiSCN, LiCl, LiCF3SO3, LiCF3CO2, LiN(CF3SO2)2, LiAsF6, LiBC4O8, and LiN(FSO2)2.

[0021] Optionally, in some embodiments, the solvent includes one or more of ether solvents, ester solvents, sulfone solvents, and ionic liquid solvents, wherein:

[0022] The ether solvents include one or more of dimethyl ether, ethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, ethylene glycol dibutyl ether, 2,2,2-trifluoroethyl ether, ethylene glycol bis(propionitrile) ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, and triethylene glycol dimethyl ether; and / or

[0023] The ester solvents include one or more of the following: ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, propylene carbonate, fluoroethylene carbonate, methyl trifluoroethyl carbonate, difluoroethylene carbonate, tris(2,2,2-trifluoroethyl) phosphate, bis(2,2,2-trifluoroethyl) carbonate, and ethyl trifluoroacetate; and / or

[0024] The sulfone solvent includes one or more of sulfolane and dimethyl sulfoxide; and / or

[0025] The ionic liquid solvent includes one or more of the following: 1-methyl-1-propylpyrrolidine bis(fluorosulfonyl)imide, 1-methyl-1-propylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, N-propyl-N-methylpyrrolidine hexafluorophosphate, N-butyl-N-methylpyrrolidine hexafluorophosphate, and N-ethyl-N-methylpyrrolidine bis(fluorosulfonyl)imide.

[0026] Accordingly, this application also provides a battery including the solid electrolyte. Beneficial effects

[0027] The solid electrolyte precursor solution described in this application uses pentaerythritol glycidyl ether as a monomer. The molecular structure of pentaerythritol glycidyl ether has four three-membered ring ethers, which greatly improves the monomer utilization rate. With the addition of a small amount of monomer, the solid electrolyte precursor solution can be completely polymerized, thereby improving the ionic conductivity of the prepared solid electrolyte, reducing the internal resistance of the battery including the solid electrolyte, improving the battery's capacity retention and rate performance, and broadening the battery's electrochemical window.

[0028] Furthermore, based on the superior polymerization characteristics of pentaerythritol glycidyl ether, the solid electrolyte precursor solution only needs to add this one monomer to polymerize, and the resulting solid electrolyte has no residual liquid, which can effectively avoid the safety problems caused by residual liquid leakage in the solid electrolyte.

[0029] Furthermore, this application uses only lithium difluorooxalate borate as an initiator, without the need for other initiators, to effectively initiate the polymerization of pentaerythritol glycidyl ether. In addition, lithium difluorooxalate borate can also act as a lithium salt additive, which can effectively avoid the impact of the use of other initiators on the performance of the solid electrolyte. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 is a flowchart of a method for preparing a solid electrolyte according to an embodiment of this application;

[0032] Figure 2 is a flowchart of a battery preparation method provided in an embodiment of this application;

[0033] Figure 3 is a diagram showing the complete solidification of the solid electrolyte precursor solution in Example 1 of this application;

[0034] Figure 4 is a diagram of the solid electrolyte precursor solution of Comparative Example 2 of this application before it is completely solidified;

[0035] Figure 5 is a diagram of the solid electrolyte precursor solution of Comparative Example 7 of this application solidifying in layers.

[0036] Implementation methods of this application

[0037] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application.

[0038] In this application, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in its actual use or operating state, specifically the drawing directions in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc., are used merely as illustrative purposes and do not impose numerical requirements or establish a numerical order.

[0039] In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.

[0040] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c," or "at least one of a, b, and c," can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0041] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0042] The technical solution of this application is as follows:

[0043] In a first aspect, embodiments of this application provide a solid electrolyte precursor solution for preparing a solid electrolyte. The solid electrolyte precursor solution comprises a lithium salt solution, a monomer, and an initiator, wherein the lithium salt solution comprises a lithium salt and a solvent, the initiator is lithium difluorooxalate borate (LIDFOB), and the monomer is pentaerythritol glycidyl ether.

[0044] The solid electrolyte precursor solution described in this application uses pentaerythritol glycidyl ether as a monomer. The molecular structure of pentaerythritol glycidyl ether has four three-membered ring ethers, which greatly improves the monomer utilization rate. With the addition of a small amount of monomer, the solid electrolyte precursor solution can be completely polymerized, thereby improving the ionic conductivity of the prepared solid electrolyte, reducing the internal resistance of the battery including the solid electrolyte, improving the battery's capacity retention and rate performance, and broadening the battery's electrochemical window.

[0045] Furthermore, based on the superior polymerization characteristics of pentaerythritol glycidyl ether, the solid electrolyte precursor solution only needs to add this one monomer to polymerize, and the resulting solid electrolyte has no residual liquid, which can effectively avoid the safety problems caused by residual liquid leakage in the solid electrolyte.

[0046] Furthermore, this application uses only lithium difluorooxalate borate as an initiator, without the need for other initiators, to effectively initiate the polymerization of pentaerythritol glycidyl ether. In addition, lithium difluorooxalate borate can also act as a lithium salt additive, which can effectively avoid the impact of the use of other initiators on the performance of the solid electrolyte.

[0047] In some embodiments, the mass ratio of the lithium salt to the solvent in the lithium salt solution is (0.08–0.25):1, for example, 0.08:1, 0.09:1, 0.1:1, 0.11:1, 0.12:1, 0.13:1, 0.14:1, 0.15:1, 0.16:1, 0.17:1, 0.18:1, 0.19:1, 0.2:1, 0.21:1, 0.22:1, 0.23:1, 0.24:1, 0.25:1, and any range between two such ratios. Within this range, the prepared solid electrolyte can have a high ionic conductivity.

[0048] In some embodiments, the mass of the initiator in the solid electrolyte precursor solution is 0.1% to 1% of the mass of the lithium salt solution, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, and any range between two values. Within this range, the prepared solid electrolyte can have a high ionic conductivity.

[0049] In some embodiments, the mass of the monomer in the solid electrolyte precursor solution is 1.5% to 8% of the mass of the lithium salt solution, for example, 1.5%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, and any range between two values. Within this range, it is beneficial for both the solid electrolyte precursor solution to solidify and for the prepared solid electrolyte to have higher ionic conductivity.

[0050] In some embodiments, the lithium salt includes, but is not limited to, one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium chloride (LiCl), lithium tetrachloroaluminate (LiAlCl4), lithium hexafluoroantimonyate (LiSbF6), lithium cyanide sulfide (LiSCN), lithium trifluoromethanesulfonate (LiCF3SO3), LiCF3CO2, lithium bis(trifluoromethanesulfonyl)imide (LiN(CF3SO2)2, abbreviated as LiTFSI), lithium hexafluoroarsenate (LiAsF6), lithium bis(oxalateborate) (LiBC4O8), and lithium bis(fluorosulfonyl)imide (LiN(FSO2)2, abbreviated as LiFSI).

[0051] In some embodiments, the solvent includes, but is not limited to, one or more of ether solvents, ester solvents, sulfone solvents, and ionic liquid solvents.

[0052] In some embodiments, the ether solvents include, but are not limited to, one or more of dimethyl ether (DME), ethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, ethylene glycol dibutyl ether, 2,2,2-trifluoroethyl ether, ethylene glycol bis(propionitrile) ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, and triethylene glycol dimethyl ether.

[0053] In some embodiments, the ester solvent includes, but is not limited to, one or more of ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), propylene carbonate (PC), fluoroethylene carbonate (FEC), methyl trifluoroethyl carbonate (FEMC), difluoroethylene carbonate (DFEC), tris(2,2,2-trifluoroethyl) phosphate (TFEP), bis(2,2,2-trifluoroethyl) carbonate (TFEC), and ethyl trifluoroacetate (ETFA).

[0054] In some embodiments, the sulfone solvent includes, but is not limited to, one or more of sulfolane and dimethyl sulfoxide.

[0055] In some embodiments, the ionic liquid solvent includes, but is not limited to, one or more of 1-methyl-1-propylpyrrolidine bis(fluorosulfonyl)imide, 1-methyl-1-propylpyrrolidine bis(trifluoromethanesulfonyl)imide, N-propyl-N-methylpyrrolidine hexafluorophosphate, N-butyl-N-methylpyrrolidine hexafluorophosphate, and N-ethyl-N-methylpyrrolidine bis(fluorosulfonyl)imide.

[0056] It is understood that the organic solvent can be a single solvent or a mixture of solvents. In some embodiments, the organic solvent is a mixture of solvents. Further, in at least some embodiments, the mixture of solvents is a mixture of ethylene carbonate, diethyl carbonate, and fluoroethylene carbonate, and the volume ratio of ethylene carbonate, diethyl carbonate, and fluoroethylene carbonate is 4:4:2.

[0057] In some embodiments, the method for preparing the solid electrolyte precursor solution includes: mixing lithium salt, monomer, initiator and solvent in a certain proportion to obtain the solid electrolyte precursor solution.

[0058] In at least one embodiment, the method for preparing the solid electrolyte precursor solution includes: mixing lithium salt and solvent in a certain proportion to obtain a lithium salt solution, and adding monomer and initiator to the lithium salt solution in a certain proportion to obtain the solid electrolyte precursor solution.

[0059] Secondly, referring to Figure 1, this application provides a method for preparing a solid electrolyte, including the following steps:

[0060] Step S11: Provide a solid electrolyte precursor solution;

[0061] Step S12: Solidify the solid electrolyte precursor solution to obtain a solid electrolyte.

[0062] The solid electrolyte precursor solution is as described above and will not be repeated here.

[0063] In some embodiments, the thermosetting is stopped when the cured texture does not change over time.

[0064] In some embodiments, the method of solidifying the solid electrolyte precursor solution includes thermal curing.

[0065] In some embodiments, the temperature range for thermal curing is 40–120°C, for example, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, or any range between two values; the time range for thermal curing is 2–18 hours, for example, 2 hours, 3 hours, 5 hours, 6 hours, 8 hours, 10 hours, 12 hours, 13 hours, 15 hours, 16 hours, 18 hours, or any range between two values. Within these temperature and time ranges, it is beneficial for the solid electrolyte precursor solution to fully solidify, resulting in a solid electrolyte with no significant liquid flow and for the prepared solid electrolyte to have a high ionic conductivity.

[0066] The solid electrolyte preparation method described in this application uses pentaerythritol glycidyl ether as a monomer in the solid electrolyte precursor solution. The molecular structure of pentaerythritol glycidyl ether has four three-membered ring ethers, which greatly improves the monomer utilization rate. With the addition of a small amount of monomer, the solid electrolyte precursor solution can be completely polymerized, thereby improving the ionic conductivity of the prepared solid electrolyte, reducing the internal resistance of the battery including the solid electrolyte, improving the battery capacity retention and rate performance, and broadening the electrochemical window of the battery.

[0067] Furthermore, based on the superior polymerization characteristics of pentaerythritol glycidyl ether, the solid electrolyte precursor solution only needs to add this one monomer to polymerize, and the resulting solid electrolyte has no residual liquid, which can effectively avoid the safety problems caused by residual liquid leakage in the solid electrolyte.

[0068] Furthermore, this application uses only LIDFOB as an initiator, without the need for other initiators, to effectively initiate the polymerization of pentaerythritol glycidyl ether. LIDFOB can also act as a lithium salt additive, effectively avoiding the impact of other initiators on the performance of the solid electrolyte.

[0069] Thirdly, embodiments of this application also provide a solid electrolyte, which is prepared by the above-described preparation method.

[0070] Fourthly, embodiments of this application also provide a battery, including a positive electrode, a negative electrode, a separator, and the solid electrolyte described above.

[0071] In some embodiments, the battery is a lithium-ion battery.

[0072] The anode includes an anode current collector and an anode active material bonded to at least one surface of the anode current collector.

[0073] The material of the anode current collector may include, but is not limited to, at least one of the materials known in the art for use in anode current collectors, such as copper, nickel, stainless steel, and titanium.

[0074] The anolyte may include, but is not limited to, at least one of graphite-based carbon materials, non-graphite-based carbon materials, metallic lithium, lithium alloys, silicon-based alloys, tin-based alloys, conductive oxides, and conductive polymers. The conductive oxide may include, but is not limited to, Li. x Fe2O3, Li x At least one of WO2, SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, and Bi2O5, wherein 0 < x < 1; the conductive polymer may include, but is not limited to, at least one of polyacetylene, polyaniline, and polythiophene.

[0075] The cathode includes a cathode current collector and a cathode active material bonded to at least one surface of the cathode current collector.

[0076] The material of the cathode current collector may include, but is not limited to, at least one material known in the art for use in cathode current collectors, such as aluminum and nickel.

[0077] The cathode active material may include, but is not limited to, at least one of lithium iron phosphate, lithium manganese oxide, lithium manganese iron phosphate, nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, sodium vanadium phosphate, sodium iron pyrophosphate, Prussian white, sodium cobalt oxide, and sodium nickel iron manganese oxide. Specifically, the cathode active material may include, but is not limited to, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, and Li(Ni a Co b Mn c O2, LiNi a Co b Al c O2, LiNi y Co 1-y O2, LiCo y Mn 1-y O2, LiCo y Al 1-y O2, LiCo y B 1-y O2, LiCo y Mg 1-y O2, LiCo y Ti 1-y O2, LiCo y Mo 1-y O2, LiCo y Sn 1-y O2, LiCoy Ca 1-y O2, LiCo y Cu 1-y O2, LiCo y V 1-y O2, LiCo y Zr 1-y O2, LiCo y Si 1-y O2, LiCo y W 1-y O2, LiCo y Y 1-y O2, LiCo y La 1-y O2, LiCo y Mn 1-y O2, LiNi y Mn 1-y O2, LiCoPO4, LiFePO4, LiMn y Fe 1-y PO4, Na3V2(PO4)3, Na8Fe4(P2O7)5, Na2Fe2(Fe(CN)6)3, Na(Ni a Fe b Mn c At least one of O2. Wherein, 0 < a < 1, 0 < b < 1, a + b + c = 1, 0 < y < 1.

[0078] It is understood that the separator can be a known separator used in batteries, such as one or more of oxide-based solid electrolyte separators, glass-based solid electrolyte separators, polymer-based solid electrolyte separators, and carbon-based solid electrolyte separators. The materials of the oxide-based solid electrolyte separators include, but are not limited to, one or more of zirconium oxide and perovskite oxide. The materials of the glass-based solid electrolyte separators include, but are not limited to, one or more of silicate glass and phosphate glass. The materials of the polymer-based solid electrolyte separators include, but are not limited to, one or more of polyethylene oxide (PEO) and polyacrylonitrile (PAN). The materials of the carbon-based solid electrolyte separators include, but are not limited to, one or more of carbon nanotubes and graphene.

[0079] Fifthly, referring to Figure 2, this application also provides a method for preparing a battery, including the following steps:

[0080] Step S21: Provide a battery casing including a positive electrode, a negative electrode, and a separator;

[0081] Step S22: Inject a solid electrolyte precursor solution into the battery casing to convert the solid electrolyte precursor solution into a solid electrolyte, thereby obtaining the battery.

[0082] The positive electrode, the negative electrode, the separator, and the solid electrolyte precursor solution are described above and will not be repeated here.

[0083] In some embodiments, the method of converting the solid electrolyte precursor solution into a solid electrolyte includes thermal curing.

[0084] In some embodiments, the temperature range for thermal curing is 40–120°C, for example, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, or any range between two values; the time range for thermal curing is 2–18 hours, for example, 2 hours, 3 hours, 5 hours, 6 hours, 8 hours, 10 hours, 12 hours, 13 hours, 15 hours, 16 hours, 18 hours, or any range between two values. Within these temperature and time ranges, it is beneficial for the solid electrolyte precursor solution to be fully cured, which in turn is beneficial for the prepared solid electrolyte to have a higher ionic conductivity, and consequently, for the prepared battery to have better capacity retention and other electrical properties.

[0085] The battery described in this application is prepared by in-situ solidification of the solid electrolyte precursor solution. The solid electrolyte precursor solution uses pentaerythritol glycidyl ether as a monomer. The molecular structure of pentaerythritol glycidyl ether has four three-membered ring ethers, which greatly improves the monomer utilization rate. With the addition of a small amount of monomer, the solid electrolyte precursor solution can be completely polymerized, thereby improving the ionic conductivity of the prepared solid electrolyte, reducing the internal resistance of the battery including the solid electrolyte, improving the battery's capacity retention and rate performance, and broadening the battery's electrochemical window.

[0086] Furthermore, based on the superior polymerization characteristics of pentaerythritol glycidyl ether, the solid electrolyte precursor solution only needs to add this one monomer to polymerize, and the resulting solid electrolyte has no residual liquid, which can effectively avoid the safety problems caused by residual liquid leakage in the solid electrolyte.

[0087] Furthermore, this application uses only lithium difluorooxalate borate as an initiator, without the need for other initiators, to effectively initiate the polymerization of pentaerythritol glycidyl ether. In addition, lithium difluorooxalate borate can also act as a lithium salt additive, which can effectively avoid the impact of the use of other initiators on the performance of the solid electrolyte.

[0088] The present application will be specifically described below through specific embodiments. The following embodiments are only some embodiments of the present application and are not intended to limit the present application.

[0089] Example 1

[0090] The method for preparing the solid electrolyte precursor solution in this embodiment includes:

[0091] EC, DEC and FEC are mixed in a volume ratio of 4:4:2 to obtain a solvent. LiPF6 is added to the solvent, wherein the mass ratio of LiPF6 to the solvent is 0.125:1. After stirring evenly, a lithium salt solution is obtained.

[0092] LIDFOB and pentaerythritol glycidyl ether are added to the lithium salt solution, wherein the mass of LIDFOB is 0.2% of the mass of the lithium salt solution and the mass of pentaerythritol glycidyl ether is 2% of the mass of the lithium salt solution, to obtain a solid electrolyte precursor solution.

[0093] Example 2

[0094] This embodiment is basically the same as Embodiment 1, except that the lithium salt solution in this embodiment includes lithium salt LiFSI, and solvents DME and TTE, wherein the volume ratio of DME to TTE is 1:3.62, and the mass ratio of LiFSI to solvent is 1:4.3.

[0095] Example 3

[0096] This embodiment is basically the same as that of embodiment 1, except that the solvent in this embodiment includes TMS and FEC in a volume ratio of 6:2, the lithium salt in this embodiment is LiTFSI, and the mass of LiTFSI is 22% of the mass of the solvent.

[0097] Example 4

[0098] This embodiment is basically the same as Embodiment 1, except that in this embodiment, the mass of LIDFOB is 0.1% of the mass of the lithium salt solution.

[0099] Example 5

[0100] This embodiment is basically the same as Embodiment 1, except that in this embodiment, the mass of LIDFOB is 0.5% of the mass of the lithium salt solution.

[0101] Example 6

[0102] This embodiment is basically the same as Embodiment 1, except that in this embodiment, the mass of LIDFOB is 1% of the mass of the lithium salt solution.

[0103] Example 7

[0104] This embodiment is basically the same as Embodiment 1, except that in this embodiment, the mass of pentaerythritol glycidyl ether is 1.5% of the mass of the lithium salt solution.

[0105] Example 8

[0106] This embodiment is basically the same as that of Embodiment 1, except that in this embodiment, the mass of pentaerythritol glycidyl ether is 4% of the mass of the lithium salt solution.

[0107] Example 9

[0108] This embodiment is basically the same as that of Embodiment 1, except that in this embodiment, the mass of pentaerythritol glycidyl ether is 8% of the mass of the lithium salt solution.

[0109] Comparative Example 1

[0110] This comparative example is basically the same as Example 1, except that 1,3,5-trioxane is used to replace pentaerythritol glycidyl ether in Example 1.

[0111] Comparative Example 2

[0112] This comparative example is basically the same as Example 1, except that in this comparative example, the mass of LIDFOB is 0.05% of the mass of the lithium salt solution.

[0113] Comparative Example 3

[0114] This comparative example is basically the same as Example 1, except that in this comparative example, the mass of LIDFOB is 1.5% of the mass of the lithium salt solution.

[0115] Comparative Example 4

[0116] This comparative example is basically the same as Example 1, except that in this comparative example, the mass of pentaerythritol glycidyl ether is 1% of the mass of the lithium salt solution.

[0117] Comparative Example 5

[0118] This comparative example is basically the same as Example 1, except that in this comparative example, the mass of pentaerythritol glycidyl ether is 10% of the mass of the solvent.

[0119] Comparative Example 6

[0120] This comparative example is basically the same as Example 1, except that in this comparative example, the cyclic ether monomer DOX (1,3-dioxane) is used to replace the pentaerythritol glycidyl ether in Example 1.

[0121] Comparative Example 7

[0122] This comparative example is basically the same as Example 1, except that in this comparative example, the monomer PETEA (pentaerythritol tetraacrylate) polymerized in a ring-opening manner is used to replace pentaerythritol glycidyl ether in Example 1.

[0123] Comparative Example 8

[0124] This comparative example is basically the same as Example 1, except that in this comparative example, the initiator Al(OTF)3 (aluminum trifluoromethanesulfonate) is used instead of the initiator LIDFOB in Example 1.

[0125] Performance testing:

[0126] Solid electrolyte precursor solutions from Examples 1-9 and Comparative Examples 1-8 were cured at 80°C for 3 hours to obtain solid electrolytes. The curing state was observed, and the results are shown in Table 1 and Figures 3 to 4. Figure 3 shows the completely cured solid electrolyte precursor solution from Example 1, Figure 4 shows the partially cured solid electrolyte precursor solution from Comparative Example 2, and Figure 5 shows the layered curing of the solid electrolyte precursor solution from Comparative Example 7.

[0127] The solid electrolytes of Examples 1-9 and Comparative Examples 1-8 were subjected to ionic conductivity RT tests at a temperature of 25°C. The test results are shown in Table 1.

[0128] The solid-state batteries of Examples 1-9 and Comparative Examples 1-8 were subjected to electrical performance tests to obtain the capacity retention rate of the batteries after 60 cycles. The test results are shown in Table 1.

[0129] The method for testing ionic conductivity is as follows: Assemble a coin cell in the following order: positive electrode shell, gasket, PP separator, precursor solution, gasket, spring contact, and negative electrode shell. The amount of precursor solution is 80 μL. After assembly, allow the cell to stand for 8 hours. Perform AC impedance testing at room temperature using an electrochemical workstation. The AC voltage is 5 mV, and the test frequency is from 0.1 Hz to 100 kHz to obtain the R value. Then, calculate the ionic conductivity using the following formula:

[0130] Where σ is the ionic conductivity, R is the bulk resistance, L is the thickness of the PP diaphragm, and S is the area of ​​the spring sheet.

[0131] The method for testing electrical performance was as follows: batteries were assembled using the solid electrolyte precursor solutions of Examples 1-9 and Comparative Examples 1-8, respectively. The positive electrode used NCM811 ternary material, and the ternary material loading was 3.2 mAh / cm³. 2 The negative electrode uses 20μm lithium metal, and the separator uses PP film. After assembly, it is left to stand for 24 hours, and then placed at 80℃ for 3 hours to allow the solid electrolyte precursor solution to undergo a solidification reaction, thereby forming a quasi-solid-state battery. Then, the battery cycle test is carried out using a Blue Electric Cycling Tester with a charge of 0.33C and a discharge of 1C.

[0132] Table 1:

[0133] In Comparative Examples 2 and 4, the ionic conductivity and capacity retention were not tested because the solid electrolyte precursor solution could not be completely solidified and thus could not form a solid electrolyte.

[0134] As shown in Table 1:

[0135] Compared to the solid electrolytes prepared from the solid electrolyte precursor solutions of Comparative Examples 1-8, the solid electrolytes prepared from the solid electrolyte precursor solutions of Examples 1-9 exhibit higher ionic conductivity. This demonstrates that the solid electrolytes prepared using the solid electrolyte precursor solutions described in this application have higher ionic conductivity. The reasons for this may be: the solid electrolyte precursor solutions described in this application use pentaerythritol glycidyl ether as a monomer. The molecular structure of pentaerythritol glycidyl ether contains four three-membered ring ethers, significantly improving monomer utilization. With only a small amount of monomer added, the solid electrolyte precursor solution can be completely polymerized, thereby increasing the ionic conductivity of the prepared solid electrolyte. Furthermore, this application uses only lithium difluorooxalate borate as an initiator, eliminating the need for other initiators, effectively initiating the polymerization of pentaerythritol glycidyl ether. Lithium difluorooxalate borate also acts as a lithium salt additive, effectively avoiding the impact of other initiators on the performance of the solid electrolyte.

[0136] Compared to the batteries prepared with solid electrolyte precursor solutions in Comparative Examples 1-8, the batteries prepared with solid electrolyte precursor solutions in Examples 1-9 have a higher capacity retention rate at 60 cycles. It can be seen that the batteries prepared with the solid electrolyte precursor solution described in this application have a higher capacity retention rate. The reason may be that the solid electrolyte prepared with the solid electrolyte precursor solution described in this application has a higher ionic conductivity.

[0137] The technical solutions provided by the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A solid electrolyte precursor solution, wherein, The mixture includes a lithium salt solution, pentaerythritol glycidyl ether, and lithium difluorooxalate borate, wherein the lithium salt solution comprises a lithium salt and a solvent.

2. The solid electrolyte precursor solution as described in claim 1, wherein, The mass ratio of the lithium salt to the solvent is (0.08–0.25):

1.

3. The solid electrolyte precursor solution as described in claim 1, wherein, The mass of the lithium difluorooxalate borate is 0.1% to 1% of the mass of the lithium salt solution.

4. The solid electrolyte precursor solution as described in claim 1, wherein, The mass of the pentaerythritol glycidyl ether is 1.5 to 8% of the mass of the lithium salt solution.

5. The solid electrolyte precursor solution as described in claim 1, wherein, The lithium salt includes one or more of LiPF6, LiBF4, LiCl, LiAlCl4, LiSbF6, LiSCN, LiCl, LiCF3SO3, LiCF3CO2, LiN(CF3SO2)2, LiAsF6, LiBC4O8, and LiN(FSO2)2.

6. The solid electrolyte precursor solution as described in claim 1, wherein, The solvent includes one or more of the following: ether solvents, ester solvents, sulfone solvents, and ionic liquid solvents.

7. The solid electrolyte precursor solution as described in claim 6, wherein, The ether solvents include one or more of dimethyl ether, ethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, ethylene glycol dibutyl ether, 2,2,2-trifluoroethyl ether, ethylene glycol bis(propionitrile) ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, and triethylene glycol dimethyl ether.

8. The solid electrolyte precursor solution as described in claim 6, wherein, The ester solvents include one or more of the following: ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, propylene carbonate, fluoroethylene carbonate, methyl trifluoroethyl carbonate, difluoroethylene carbonate, tris(2,2,2-trifluoroethyl) phosphate, bis(2,2,2-trifluoroethyl) carbonate, and ethyl trifluoroacetate.

9. The solid electrolyte precursor solution as described in claim 6, wherein, The sulfone solvents include one or more of sulfolane and dimethyl sulfoxide.

10. The solid electrolyte precursor solution as described in claim 6, wherein, The ionic liquid solvent includes one or more of the following: 1-methyl-1-propylpyrrolidine bis(fluorosulfonyl)imide, 1-methyl-1-propylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, N-propyl-N-methylpyrrolidine hexafluorophosphate, N-butyl-N-methylpyrrolidine hexafluorophosphate, and N-ethyl-N-methylpyrrolidine bis(fluorosulfonyl)imide.

11. A solid electrolyte, wherein, The solid electrolyte is obtained by solidifying a solid electrolyte precursor solution, which includes a lithium salt solution, pentaerythritol glycidyl ether, and lithium difluorooxalate borate, wherein the lithium salt solution includes a lithium salt and a solvent.

12. The solid electrolyte of claim 11, wherein, The mass ratio of the lithium salt to the solvent is (0.08–0.25):

1.

13. The solid electrolyte of claim 11, wherein, The mass of the lithium difluorooxalate borate is 0.1% to 1% of the mass of the lithium salt solution.

14. The solid electrolyte of claim 11, wherein, The mass of the pentaerythritol glycidyl ether is 1.5 to 8% of the mass of the lithium salt solution.

15. The solid electrolyte of claim 11, wherein, The lithium salt includes one or more of LiPF6, LiBF4, LiCl, LiAlCl4, LiSbF6, LiSCN, LiCl, LiCF3SO3, LiCF3CO2, LiN(CF3SO2)2, LiAsF6, LiBC4O8, and LiN(FSO2)2.

16. The solid electrolyte of claim 11, wherein, The solvent includes one or more of the following: ether solvents, ester solvents, sulfone solvents, and ionic liquid solvents, wherein: The ether solvents include one or more of dimethyl ether, ethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, ethylene glycol dibutyl ether, 2,2,2-trifluoroethyl ether, ethylene glycol bis(propionitrile) ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, and triethylene glycol dimethyl ether; and / or The ester solvents include one or more of the following: ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, propylene carbonate, fluoroethylene carbonate, methyl trifluoroethyl carbonate, difluoroethylene carbonate, tris(2,2,2-trifluoroethyl) phosphate, bis(2,2,2-trifluoroethyl) carbonate, and ethyl trifluoroacetate; and / or The sulfone solvent includes one or more of sulfolane and dimethyl sulfoxide; and / or The ionic liquid solvent includes one or more of the following: 1-methyl-1-propylpyrrolidine bis(fluorosulfonyl)imide, 1-methyl-1-propylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, N-propyl-N-methylpyrrolidine hexafluorophosphate, N-butyl-N-methylpyrrolidine hexafluorophosphate, and N-ethyl-N-methylpyrrolidine bis(fluorosulfonyl)imide.

17. A battery, wherein, Includes the solid electrolyte as described in any one of claims 11 to 16.

Images